Field of the Disclosure
The present disclosure, for example, relates to wireless communication systems, and more particularly to enabling a device-to-device discovery procedure.
Description of Related Art
Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems.
By way of example, a wireless multiple-access communication system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipments (UEs). A base station may communicate with UEs on downlink channels (e.g., for transmissions from a base station to a UE) and uplink channels (e.g., for transmissions from a UE to a base station).
Typically, UEs engage in wireless communication by communicating with a base station of a wireless communications system. However, UEs may also participate in direct D2D or ProSe wireless communications. D2D discovery allows UEs that are within range of each other to communicate directly with each other instead of communicating through a base station. One UE may broadcast a D2D discovery announcement, such as a Direct Peer-Discovery Signal in a Long Term Evolution (LTE) system, which may then be received by the neighboring UEs in the proximity that are monitoring such discovery communications. A monitoring UE may receive the D2D discovery announcement and perform an association procedure to authenticate and establish communications with the announcing UE. Such discovery procedures, however, become problematic when the announcing UE and the monitoring UE are operating on different frequencies and, in some situations, via different carriers. For example, a monitoring UE that is camped on and communicating with a serving base station may need to tune to the frequency of the announcing UE to detect the discovery signal, which may disrupt communications with the serving base station.